Abstract [en]

Kallerstad landfill was in use between 1950 and 1973. Nonetheless, assessment of closed landfills and their risk to the environment and health is required. Firstly, the levels of zinc, nickel, arsenic, copper, ammonia, TOT-N and TOC in the surface water of the main recipient Kallerstadsdiket, were compared to cut-off levels given by the Swedish Agency for Marine and Water Management. Then, the direct contribution of Kallerstad landfill to the contamination level was estimated. Finally, the contamination load that flows from Kallerstadsdiket to Stångån, which is a second recipient with high natural value, was estimated. Zinc, nickel and copper showed low levels and low risk at all sampling stations. Ammonia and arsenic showed higher levels and a potential risk of adverse effects. As a result, the surface water in Kallerstadsdiket could not be classified to reach ‘good’ status, although the direct role that Kallerstad landfill plays is doubtful. Calculations suggest that Kallerstad landfill does add arsenic and TOC to the contamination levels, although in small amounts. The risk of spread of contaminants to Stångån was estimated to be low. The additional contamination levels stemming from Kallerstadsdiket are lower than the levels measured in Stångån. The dilution factor was estimated to be 1:320. Nevertheless, the current study has many uncertainties that are mainly related to data availability. It is therefore recommended to apply a more complete sampling scheme with the appropriate parameters (e.g., pH, DOC, Ca, and temperature) in all sampling stations. Ideally it would be plausible to sample every week for a period of a year and then reassess the risk, as well as to get a more reliable approximation of the contribution of the landfill itself.